ATAR Notes: Forum

Archived Discussion => HSC Exam Discussion 2020 => Exam Discussions => New South Wales => Maths Exams => Topic started by: Joseph41 on October 26, 2020, 09:02:25 am

Title: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: Joseph41 on October 26, 2020, 09:02:25 am
Good luck everybody! :)

When the exam has finished, use this thread to chat all things Maths Extension 2.
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: RuiAce on October 26, 2020, 06:12:53 pm
Alright somehow this ended up being the first paper that landed in my hands, so here goes. Let me know of any mistakes along the way.

Uploading will be done by my beloved insanipi this year.

Multiple choice
Spoiler
(https://i.imgur.com/nzt25Zb.png)

Short answer - check back periodically!
Question 11
(https://i.imgur.com/GMaAMnm.png)
Question 12
(https://i.imgur.com/VVKOgfa.png)
Question 13
(https://i.imgur.com/8eHhyX5.png)
Question 14
(https://i.imgur.com/bfC4Omu.png)
Question 15
(https://i.imgur.com/SWRE0yP.png)
Question 16
Part A
(https://i.imgur.com/lShsIGM.png)

Part B
(https://i.imgur.com/1ccXx0c.png)
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: HeyyyIts2xq on October 26, 2020, 09:23:30 pm
Sorry. Just something I've noticed. You made the Amplitude of motion for Q13a) root3. In the question, it says that the max displacement is 2root3 from the centre point of motion. Wouldn't that mean 2root3 is the amplitude?
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: RuiAce on October 26, 2020, 09:35:03 pm
Sorry. Just something I've noticed. You made the Amplitude of motion for Q13a) root3. In the question, it says that the max displacement is 2root3 from the centre point of motion. Wouldn't that mean 2root3 is the amplitude?
Caught that just now actually. Thanks for mentioning it! An amended solution will appear shortly.
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: mrsc on October 26, 2020, 09:38:39 pm
Also shouldn't n equal 6 and not 2/3 for the SHM question?
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: RuiAce on October 26, 2020, 09:41:56 pm
Also shouldn't n equal 6 and not 2/3 for the SHM question?
Should also be fixed in the latest version
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: pm2003 on October 26, 2020, 11:10:33 pm
do u know how many marks these questions were?
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: RuiAce on October 27, 2020, 12:05:35 am
Overalls were

Q11: 16
Q12: 14
Q13: 15
Q14: 16
Q15: 13
Q16: 16

Was there any part you were interested in?
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: pm2003 on October 27, 2020, 12:23:23 am
Overalls were

Q11: 16
Q12: 14
Q13: 15
Q14: 16
Q15: 13
Q16: 16

Was there any part you were interested in?

13 and 15 please :) thank you so much
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: RuiAce on October 27, 2020, 01:24:27 am
13 and 15 please :) thank you so much
Q13 parts:
a) 3
b) 3
c) 2,1
d) 1,3,2

Q15
a) 2,1,3
b) 2,1,3,1
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: pm2003 on October 27, 2020, 11:55:19 am
thank you!  :)
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: Gli1 on October 27, 2020, 12:57:34 pm
What do you reckon the cut off for this year will be for 4u since everyone on Facebook is bluffing
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: HeyyyIts2xq on October 27, 2020, 02:48:58 pm
Judges (i.e. extremely experienced teachers) will determine what a B6, B5 etc. students should show in terms of syllabus outcomes. These will then allow for the judge to decide what mark is a B6 B5 etc. These raw marks then get aligned to their respective positions.
i.e. 90-100 B6 etc.
This applies to E4 E3 etc. as well (i.e. extension subjects)

Now from my viewpoint, I see that the cutoff for E4 from past years have hanged approximately around 75ish. With that being said, my prediction is that it'll still be around this range.

Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: DarkWorld on October 27, 2020, 03:19:52 pm
Welp. That's 10 marks lost from Q16 and 2 in multis.
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: RuiAce on October 27, 2020, 04:29:13 pm
What do you reckon the cut off for this year will be for 4u since everyone on Facebook is bluffing
I think a lot of people underestimate the paper's difficulty. It leaned on the easier end of things, but I didn't really feel it was a blessing or anything.

I feel like worst case E4 cut-off would be around 81. I still think high end 70s should be enough. But who knows; won't find out until release of results day at earliest.
Welp. That's 10 marks lost from Q16 and 2 in multis.
Q16b felt like a question where you really had to show algebraic skill tbh.

Admittedly Q16a(i) sent my head spinning for a while before I finally understood what was going on.
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: JedToner on October 27, 2020, 04:54:42 pm
Could anyone post a pdf of the paper by any chance???
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: DarkWorld on October 27, 2020, 04:59:01 pm
I think a lot of people underestimate the paper's difficulty. It leaned on the easier end of things, but I didn't really feel it was a blessing or anything.

Admittedly Q16a(i) sent my head spinning for a while before I finally understood what was going on.

Yeah unfortunately my first mistake was straight up integrating by parts instead of integrating a single sin(x) to be dcosx then doing by parts. Second mistake was converting cos(2\theta) to 2sin^2(\theta)-1.
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: sweetiepi on October 27, 2020, 09:06:50 pm
Could anyone post a pdf of the paper by any chance???
Unfortunately, NESA exams are copyrighted, so they cannot be distributed on the forum. :)
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: RuiAce on October 27, 2020, 09:10:51 pm
Yeah unfortunately my first mistake was straight up integrating by parts instead of integrating a single sin(x) to be dcosx then doing by parts. Second mistake was converting cos(2\theta) to 2sin^2(\theta)-1.
Ah that's very unfortunate indeed. The method for \( I_n = \int \sin^n x\,dx \) is actually one of the classic trig function reductions.

Trig identities do get nasty. I've done them so many times and I still make minor errors occasionally.
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: DarkWorld on October 27, 2020, 09:35:24 pm
Unfortunately, NESA exams are copyrighted, so they cannot be distributed on the forum. :)

God damn it!
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: RuiAce on October 28, 2020, 03:01:22 pm
An official copy of the paper has been released.
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: Paradoxica on October 30, 2020, 01:44:18 am
the look on my face when i see that the NESA paper and the BOS paper have the same integral
Title: Re: Maths Extension 2 - Discussion, Questions, Potential Solutions
Post by: HUA0007 on July 28, 2021, 05:23:29 pm
An official copy of the paper has been released.
HSC Math Extension 2 looks harder than VIC Spec Maths.